Hi, Hank: I check the ohms on the coil pack between the terminals. The reading fluctuates between 5 and 7 ohms. Another thing I noticed was the wire 15R has 12 plus volt when the engine is not cranked. It has 11.7 volt when being cranked. Is this normal?

Hi, Hank: I should be able to find the 15R at the board right? Then I could check the pin right at the board to isolate if it is the board or the something in between. I hope it is something in between...as to board could cost me hundreds of dollars!Thank you again for taking the time answer my questions. I am so glad I found you and this website!

Hi, Hank:You are probably correct. Something is causing the relay to get stuck then. I purchased a brand new board $367.00! put it in and give me the same voltage reading! The dealer told me that the board is non-returnable...

Any idea what to check next? If you know any would buy this card let me too...

The only thing I could come up with off the top of my head now are that either the cam sensor or magnetic pickup may be shorted out, causing the board to continue to send 12V to the coil pack constantly. I have honestly never seen this happen, and am not sure.

I will have to get with Generac on Monday to get the proper test procedures.

Hi, Hank:Thanks for checking at my reply on the weekend! Strange indeed! I also purchased the Diagnostic and Repair manual. I haven't seen any test procedure for for cam sensor in the manual. Please let me know what are the test procedures. I checked the Run Relay the coil and it is okay. But I have feeling something is preventing it from getting the voltage to energize it. I also don't get any voltage on the terminal 14 at the TB1. However there are voltage on 14A (coming out of the board. I don't know if any of these make any sense to you? Thanks again for help!

Thank you for the clarification. Okay this is the 14A of the 14-in connector. Okay, it is good thing there are power there. How do I check if the contact of this run relay is closing the and power is being transfer to all the necessary items? In another word which wire feeds the power to the contacts of the run relay and which one takes it out?Thanks

Test: With the relay out, if you test the wires themselves (not the relay), you should find that wire 15 (went to pin 87) should have 12V when the switch is in Auto or Manual.Result: I have 13.3V in all Auto, Off and Manual position of the switch.

Test: Wire 15A (went to pin 86) should have power when the switch is in Auto or Manual.Result: I have 13.2V in Auto and Manual postion. No voltage in Off position

Test: Wires 14 and 14A should not have power at all with the relay unplugged.Result:1. This is correct, there are power at these two points2. I get 11.9V at 14A when the engines is cranked with the relay back in place3. But there is no power at 14 when the engine cranks

I did further investigation and found the wire 14A at the Run Relay does have power when the relay is plugged-in (even without being cranked). So it is ground wire—I think the board controls it—when it should be grounded in order to energize the coil—to complete the circuit. I traced the 14A and it appears to go to the 14-pin connector.

It leads to the card again. I wonder if something external is causing the card not to ground 14A in order to energize the Run relay? Is there something else between the relay and the board?

The strange thing is that the new card don't work either. I am assuming that the engine need to be running in order to calibrate the card with Magnetic Pickup and the calibration is not the reason why the new card is not working.

Withe the rest of the checks you did, it says the relay is working correctly. Wire 15 is the power input to the relay, and wire 15A is the output. 15A should not have power in 'Off', but should in 'Auto' and 'Manual', which it does.

This goes back to either the cam sensor or magnetic pickup telling the board to keep the coil pack energized all the time.

I love being able to help people, and I love working on gensets - they are almost as important to me as my own family.

It is very satisfying to be able to help someone repair their genset, when sometimes all I have to work with is a schematic. One time, I did not even have that - all I had was 2 photos the customer posted!

Saving a customer hundreds, and a couple of times over a thousand, dollars is great.

But I have been working on these for quite some time, and have a fairly decent grasp of how they work.

If you feel my services are worth it, you will have the opportunity to increase your remuneration when we are done.

I talked to Generac, and he concurred that the issue is likely to be contained in either the magnetic pickup or the cam sensor.

Both sensors send a signal to the control board to turn the power on and off to the coil.

To test the magnetic pickup, find the small black wire #0 and the small red wire #79. Connect your meter across these 2 wires (leave them connected) and test for voltage. You should get pulses of 1 to 1-1/2 V as the engine is cranking. I am not sure if it is AC or DC, but would suspect AC.

If you are not getting these pulses, the mag is bad.

If you are getting the pulses, check both wires for continuity between the mag and the board. They go to pins 9 and 10 of the 23 pin connector. Make sure neither wire is broken.

There is no actual test for the cam sensor. All you can do is test the wires for continuity to the board. The wires are 0, 194 and 402. All three go to the 23-pin connector. 0 goes to pin 16, 194 goes to pin 7, and 402 goes to pin 17.

Make sure none of the wires are broken.

If the mag, mag wires, and cam sensor wires all test good, the cam sensor needs to be replaced.

1. Since I don't have the breakout harness to go the Mag sensor, I just pocked in a fine bare wire in the conector holes. The reading I got was 0.4 V AC, does this means the Mag Sensor is bad?

2. Checked continuity on the Mag sensor wires and they all are good.

3. Checked the continuity on the Cam sensor wires and they all are good.

Additional information about 15R wire to the coil pack: Don't know if this make any difference, the constant power—12V at this wire only happens when the switch is set to Auto or Manual postion. No power if the switch is set to Off position.

Additional question regarding the Mag sensor test:The new board that I purchase came with Generac's Product Info. Bulletin PIB07-25-SThat give the following information below but the voltage indicated was different that you suggest above. The indicates 14 VAC. See the text below from the bulletin.

Thanks. XXXXX for Installation of the Magnetic Pick-up

1. Turn the AUTO/OFF/MANUAL switch to the OFF position.2. Using a flashlight, verify a flywheel tooth is directly below the magnetic pick up hole.3. Screw the magnetic pick-up down lightly until it contacts the top of the flywheel tooth.4. Back the magnetic pick-up out one (1) full turn.

NOTE: Voltage may vary depending on theengine type.

5. Connect the (PIN#OG41800SRV) breakout harness to the magnetic pick-up in line with the engine control harness.6. Turn the AUTO/OFF/MANUAL switch to the MANUAL position to verify the unit starts.• If the unit starts, proceed to step 7.• If the unit does not start, inspect dip switches and repeat steps 1 through 6.

Magnetic pick-up adjustment for OG3958 Control board7. Turn the multi meter to read AlC Voltage and insert leads into the breakout hamess.8. Turn the AUTO/OFF/MANUAL switch to the manual position to start the unit.9. Adjust magnetic pick-up to 14 VAC +/- .5 volts @ rated speed.10. Tighten down the magnetic pick-up lock nut to prevent the magnetic pick-up from coming loose during running operations. Use blue 232 locktite, if available.

Hi, Hanks:There is may 1/8th of an inch space left between the Mag sensor and flywheel. So I don't think I can adjust it any more without damaging. I can see there are no other way to go further with the trouble shooting without changing the sensor. I have order them from mainland and will take several days before it reaches to Hawaii. I will let you know once I put in the new sensor.

To bad that Generac do not have service manual for it!

Hank, in your opinion if I were to buy another unit in the future (20 to 30 KW) which would you recommend? Servicing, repair manuals are available and something a mechanic would love to work with!

Thanks for the thoughts Hank!I call Generac's main number—1800(NNN) NNN-NNNN either I got someone with bad mode or they are not very helpful to end users. The person on the customer support keep asking me to call the dealer with zero technical help. The dealers that I found in Hawaii are not very helpful—since I purchased the unit from Grainger. I was kind of disappointed. I am glad I found you!!

I am happy with Generac first for the price...second for almost three years I never had a single problem. I will look into Onan for future purchases six or seven years down the road. Things rust very quickly here...

Good news! The Magnetic PU was the defective part. I replaced it the the Generator's engine was running! Thank yo so much for all your help!!

I did the calibration based on the document that came with the part—bulletin # XXXXX

The parts list on my unit listed the board's part number as 0G1303 and the bulletin indicated that the VAC for this card is 1VAC ±0.05 VAC.I am getting 0.929VAC when I measured the MPU voltage. It is little less than the tolerance specified. Is this okay? The gap is already pretty close between the MPU and the flywheel. I tighten it until it touched the flywheel tooth than backed one turn. Please let me know. Thanks

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